#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/time.h>
#include <string.h>
#include <math.h>

int fds[4][2] = {0}; // fds[i][0] - key, fds[i][1] - led
int ino[4][2] = {{6,5},{13,22},{19,27},{26,17}};
char sta[4], last[4] = {0};
long long  base;
float delay_calibration = 0;

#define TIME_UNIT 1000

int main(){
    float s = 1, pi = 0, i = 1.0, n = 1.0;
    while (fabs(i) >= 1e-9){
        pi += i;
        n = n + 2;
        s = -s; 
        i = s/n;
    }
    pi =4* pi;
    //printf("pi: %.6f\n",pi);
    return 0;
}
